1. Field of the Invention
The invention relates to waterproof laminates. More particularly, the invention relates to waterproof laminated panel products which are not susceptible to environmental conditions. Flooring panels are referred to through out the following disclosure in an exemplary manner, and those of ordinary skill in the art will readily appreciate that the present laminates may be used in a wide variety of applications.
2. Description of the Prior Art
Decorative laminates have found wide use as the ability to replicate natural materials has substantially improved over the years. For example, decorative laminates have replaced natural materials in the construction of furniture, cabinets, and countertops. In each of these applications, a decorative surface is applied to a substrate, namely, plywood, particle board, chipboard, medium density fiberboard, etc. Typically, a backing layer is secured to the opposite side of the substrate. Since furniture, cabinets and countertops, as well as other applications in which decorative laminates are employed, generally do not encounter destructive environmental forces, the moisture response characteristics of the decorative laminates are not a primary concern.
However, not all decorative laminates are used in environments where their exposure to moisture may be readily controlled and monitored. For example, flooring panels are constantly exposed to dual competing environments which may damage the floor. Specifically, all flooring panels are exposed to an "A environment" above the flooring panel (that is, the controlled environment commonly found in a home or office) and a "B environment" below the flooring panel (that is, the environment existing in the floor boards, concrete, crawl spaces, etc. located below the flooring panel). Most prior art flooring panels are, however, not designed to exist between the competing A and B environments. Where prior art flooring panels are designed with the competing A and B environments in mind, the prior art flooring panels employ costly and/or bulky constructions in confronting the dual environments.
Flooring panels 10 are commonly manufactured with a decorative layer 12, a substrate 13 and a backing layer 14 as shown in FIG. 1. The decorative layer 12 is commonly exposed to the A environment, which typically does not present the wealth of problems that the B environment presents to the backing layer 14, which may subsequently affect the substrate 13. The decorative layer 12 commonly consists of two layers of phenolic resin impregnated kraft paper 16, 18, a pattern layer 20, and a melamine overlay layer 22 incorporating AlO.sub.2 for wear resistance. The backing layer 14, from bottom up, is commonly composed of melamine impregnated paper 24 and two layers of phenolic resin impregnated kraft paper 26, 28. As discussed above, the substrate 13 may be chosen from a variety of materials, namely, plywood, particle board, chipboard, medium density fiberboard etc.
As those of ordinary skill in the art will certainly appreciate, the decorative and backing layers discussed above are purely exemplary. Decorative and backing layers may take various forms and employ laminate layers in a variety of combinations.
While melamine impregnated paper acts as a barrier for water, the melamine layer reacts adversely when exposed to water vapor, or relative humidity (commonly found when water attempts to escape from moist floor boards or concrete). Similarly, the phenolic layers, and even most substrates, tend to expand substantially when exposed to moisture.
In view of the panel construction commonly employed, the decorative layer, substrate and backing layer react to the difference between the two environments when the A and B environments compete. As in most circumstances where an object is pulled in opposite directions by multiple forces, a flooring panel sitting between two distinct and different environments will often fail to remain flat. For example, where excess moisture exists in the B environment, the flooring panel will generally expand along its bottom surface causing the flooring panel to warp with its lateral edges pointing upwardly (positive warping). Such warping is highly aesthetically and functionally undesirable.
Negative warping (that is, expansion of the top layer causes the edges to the panel to bow downwardly) is less common with flooring panels since the upper surface of the flooring panels are generally not exposed to the environmental conditions which could result in the expansion of the upper surface of the flooring panels. Specifically, the A environment is well controlled through the use of heating systems, air conditioners, general cleaning, and the like. For example, where water is spilled on a floor, the water will generally be wiped up or evaporate into the atmosphere before it negatively affects the top layers of the flooring panel. Similarly, relative humidity and temperature are generally controlled by those people living in the specific environment.
If moisture does enter the flooring panel from the A environment and causes the decorative layer of the flooring panel to expand and negatively warp, the warping may be easily corrected by controlling the A environment, over which people have ready control. When the A environment is controlled, excess moisture held therein is released and the flooring panel generally returns to original shape.
In addition, negative warping is generally less noticeable than positive warping. Where the center of a panel bows upwardly (negative warping), most consumers will not notice the slight roll in the flooring panel. However, the upwardly extending edges found in positively warped panels are very noticeable.
The prior art has previously attempted to remedy the problems associated with warping flooring panels by either attempting to balance the layers employed in the construction of the panels or employing strong backings which resist the warping forces created by the presence of moisture. Neither remedy has been met with total success.
While balancing is highly successful where both sides of a laminate are exposed to the same environmental conditions, balancing does not produce similar results where the top and bottom surfaces of a laminate are exposed to very different environments, and this is where warpage becomes noticeable.
The approach taken in designing backing layers when confronting moisture problems in the B environment is compounded by the testing procedures currently used throughout the industry. These testing procedures do not consider the differences between the A and B environments, but rather concentrate on the attempts to balance the expansion and contraction of the layers on opposite sides of the panel.
Specifically, conventional testing procedures suggest that the panel should be exposed to humidity levels ranging from 30% to 90% over an extended period of time. While such testing may be appropriate where the panel is to be exposed to the same environment on opposite sides, this is not the case for flooring panels. As discussed above, flooring panels are constantly exposed to two very different environments; the environment above the flooring panel (the A environment) and the environment below the flooring panel (the B environment). The prior testing procedures fail to consider the differences and, therefore, fail to properly evaluate the appropriateness of the flooring panels for actual use.
As such, a need exists for a flooring panel which is not susceptible to the harm presented by exposure to moisture. In addition, a need exits for a waterproof laminate which may be used in a wide range of applications. A need further exists for a laminate product which accounts for different environments encountered on opposite sides of the laminate product.